This invention relates to a method and apparatus for laying a submergible elongate structure upon the bed of a body of water. More particularly, the invention involves the laying of a submergible pipeline.
The increased economic and strategic importance of offshore deposits of oil and natural gas has given rise to a variety of previously unfaced problems concerning the most economical and efficient means for transporting petroleum and/or natural gas between various locations in a producing offshore field. Pipeline arrangements, of course, have been the most common proposal to deal with various transportation situations and a number of pipeline laying techniques and apparatuses have been proposed. No one arrangement, however, is ideal for all situations. For example, the technique taught in Jones et al U.S. Pat. No. 3,688,878 is a very sophisticated and successful arrangement, but requires specialized equipment. In view of this, Rochelle et al. U.S. Pat. No. 3,775,987 proposes an alternative technique which involves somewhat less sophisticated and expensive equipment and the conversion of a conventional planar deck barge to a pipeline laying barge. These two United States patents are assigned to the assignee of the present application, as are the following United States patents, each of which discloses an effective method and apparatus for laying pipelines upon the bed of a body of water: Hauber et al. U.S. Pat. No. 3,280,571; Lawrence U.S. Pat. Nos. 3,390,532 and 3,487,648; Rochelle et al. U.S. Pat. No. 3,507,126; and Lochridge U.S. Pat. No. 3,606,759.
While the proposals of the above-mentioned United States patents are effective in the situations for which they are designed, the specialized equipment and degree of sophistication evident in those patents are an incentive to devise alternative techniques for laying relatively short lengths of in-field pipelines. This is particularly true where such short lenghts of in-field pipelines are of relatively small diameter such that substantial modification of the already sophisticated equipment taught in those techniques may be required. Furthermore, sound management of assets and resources may preclude the commitment of expensive and sophisticated equipment to a pipeline laying operation where a relatively short pipeline is all that must be laid.
Even when dealing with the laying of relatively short pipelines, however, it is highly desirable to have a system for laying pipeline which permits the relatively rapid laying of the pipeline in a manner which does not expose the pipeline being laid to the risk of damage during the laying operation. Any simplified pipeline laying apparatus and method directed to the particular problem of short, small diameter pipelines, therefore, still must meet reasonable standards of efficiency and pipeline handling capabilities.